Use two columns as the combined primary key : PRIMARY KEY : Table MySQL TUTORIALS

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Use two columns as the combined primary key


mysql>
mysql> CREATE TABLE myTable
    -> (
    ->    OrderID     SMALLINT UNSIGNED NOT NULL,
    ->    ModelID     SMALLINT UNSIGNED NOT NULL,
    ->    Description VARCHAR(40),
    ->    PRIMARY KEY (OrderID, ModelID)
    -> );
Query OK, 0 rows affected (0.03 sec)

mysql>
mysql> desc myTable;
+-------------+----------------------+------+-----+---------+-------+
| Field       | Type                 | Null | Key | Default | Extra |
+-------------+----------------------+------+-----+---------+-------+
| OrderID     | smallint(5) unsigned | NO   | PRI |         |       |
| ModelID     | smallint(5) unsigned | NO   | PRI |         |       |
| Description | varchar(40)          | YES  |     | NULL    |       |
+-------------+----------------------+------+-----+---------+-------+
3 rows in set (0.02 sec)

mysql>
mysql> drop table myTable;
Query OK, 0 rows affected (0.00 sec)

mysql>